Question:`A = (x^2 + 3x - 4)/(x^2 + 7x + 12), B = (x^2 + 2x - 3)/(x^2 + 6x - 7),`
`C = (x^2 + 12x + 35)/(x^2 + 4x - 5)` তিনটি বীজগাণিতিক রাশি।
ক. A কে লঘিষ্ট আকারে প্রকাশ করো।
খ. A + B কে সরল করো।
গ. দেখাও যে, `B xx C -: (x^2 - 9)/(x - 1) = 1/(x - 3)`
Answer ক.`A = (x^2 + 3x - 4)/(x^2 + 7x + 12)`
`= (x^2 + 4x - x - 4)/(x^2 + 4x + 3x + 12)`
`= (x(x + 4) - 1 (x + 4))/(x(x + 4) + 3(x + 4))`
`= ((x + 4)(x - 1))/((x + 4)(x + 3))`
`= (x - 1)/(x + 3)` (Ans)
খ. `A + B = (x^2 + 3x - 4)/(x^2 + 7x + 12) + (x^2 + 2x - 3)/(x^2 + 6x - 7)`
`= (x - 1)/(x + 3) + (x^2 + 3x - x - 3)/(x^2 + 7x - x - 7)` [ক থেকে]
`= (x - 1)/(x + 3) + (x(x + 3) - 1(x + 3))/(x(x + 7) - 1(x + 7))`
`= (x - 1)/(x + 3) + ((x + 3) (x - 1))/((x + 7)(x - 1))`
`= (x - 1)/(x + 3) + (x + 3)/(x + 7)`
`= ((x - 1)(x + 7) + (x + 3)^2)/((x + 3) (x + 7))`
`= (x^2 + 7x - x - 7 + x^2 + 6x + 9)/(x^2 + (3 + 7)x + 3.7)`
`= (x^2 + 6x - 7 + x^2 + 6x + 9)/(x^2 + 10x + 21)`
`= (2x^2 + 12x + 2)/(x^2 + 10x + 21)` (Ans)
গ. বামপক্ষ` = B xx C -: (x^2 - 9)/(x - 1)`
`= (x^2 + 2x - 3)/(x^2 + 6x - 7) xx (x^2 + 12x + 35)/(x^2 + 4x - 5) -: (x^2 - 9)/(x - 1)`
`= (x^2 + 2x - 2)/(x^2 + 7x - x - 7) xx (x^2 + 7x + 5x + 35)/(x^2 + 5x - x - 5) -: (x - 1)/(x^2 - 9)`
`= (x^2 + 2x - 2)/(x(x + 7) - 1(x - 7)) xx (x(x + 7) + 5(x + 7))/(x(x + 5) - 1(x + 5)) xx (x - 1)/(x^2 - 3^2)`
`= (x^2 + 2x - 2)/((x + 7) (x - 1)) xx ((x + 7)(x + 5))/((x + 5)(x - 1)) xx (x - 1)/((x + 3)(x - 3))`
`= (x^2 + 2x - 3)/((x - 1)(x + 3)(x - 3))`
`= (x^2 + 2x - 3)/((x^2 + 3x - x - 3)(x - 3))`
`= (x^2 + 2x - 3)/((x^2 + 2x - 3)(x - 3))`
`= 1/(x - 3)`
= ডানপক্ষ
`:. B xx C -: (x^2 - 9)/(x - 1) `
`= 1/(x - 3)` (প্রমাণিত)